The objective of the proposed project is to compare and contrast multisensory representation of peripersonal space (PPS) in two clinical groups: adults with autism spectrum disorder (ASD) and schizophrenia (SZ). The NIMH has stressed the importance of investigations that cross diagnostic categories and identify neural substrates of symptoms that are both shared and divergent across clinical groups. This project will follow this directive and extend it by focusing on basic sensory processes, which underlie more complex behavioral phenotypes and for which the neural bases are more completely understood. The project will assess the size and gradient of PPS representation in these two groups, within the hypothetical framework that shared social deficits exhibited in both groups may arise from divergent deficits in the multisensory representation of PPS. Individuals with ASD may show smaller representations of PPS and steeper gradients between PPS and extrapersonal space (EPS), reflecting a proximal focus of attention that leads to difficulty with reciprocal social interaction. In contrast, individuals with SZ are expected to show expanded PPS representation and shallower gradients between PPS and EPS, reflecting a distal or external focus that leads to problems distinguishing ownership. Both aberrant representations are predicted to relate to the specific social deficits observed in each group. We will also explor the malleability of these representations following a period of paired visual-tactile stimulation, which has been demonstrated to alter PPS representation in adults. While this exploratory aim is not designed to assess manipulating PPS representation as a treatment, and thus does not constitute an intervention study, we will assess the relationship between changes in PPS representation and social symptoms in each group as a preliminary step in determining whether there are links between these domains in ASD and SZ.